function PerspectiveTransform(a11, a21, a31, a12, a22, a32, a13, a23, a33) {
	this.a11 = a11;
	this.a12 = a12;
	this.a13 = a13;
	this.a21 = a21;
	this.a22 = a22;
	this.a23 = a23;
	this.a31 = a31;
	this.a32 = a32;
	this.a33 = a33;
	this.transformPoints1 = function (points) {
		var max = points.length;
		var a11 = this.a11;
		var a12 = this.a12;
		var a13 = this.a13;
		var a21 = this.a21;
		var a22 = this.a22;
		var a23 = this.a23;
		var a31 = this.a31;
		var a32 = this.a32;
		var a33 = this.a33;
		for (var i = 0; i < max; i += 2) {
			var x = points[i];
			var y = points[i + 1];
			var denominator = a13 * x + a23 * y + a33;
			points[i] = (a11 * x + a21 * y + a31) / denominator;
			points[i + 1] = (a12 * x + a22 * y + a32) / denominator;
		}
	}
	this.transformPoints2 = function (xValues, yValues) {
		var n = xValues.length;
		for (var i = 0; i < n; i++) {
			var x = xValues[i];
			var y = yValues[i];
			var denominator = this.a13 * x + this.a23 * y + this.a33;
			xValues[i] = (this.a11 * x + this.a21 * y + this.a31) / denominator;
			yValues[i] = (this.a12 * x + this.a22 * y + this.a32) / denominator;
		}
	}

	this.buildAdjoint = function () {
		// Adjoint is the transpose of the cofactor matrix:
		return new PerspectiveTransform(this.a22 * this.a33 - this.a23 * this.a32, this.a23 * this.a31 - this.a21 * this.a33, this.a21 * this.a32 - this.a22 * this.a31, this.a13 * this.a32 - this.a12 * this.a33, this.a11 * this.a33 - this.a13 * this.a31, this.a12 * this.a31 - this.a11 * this.a32, this.a12 * this.a23 - this.a13 * this.a22, this.a13 * this.a21 - this.a11 * this.a23, this.a11 * this.a22 - this.a12 * this.a21);
	}
	this.times = function (other) {
		return new PerspectiveTransform(this.a11 * other.a11 + this.a21 * other.a12 + this.a31 * other.a13, this.a11 * other.a21 + this.a21 * other.a22 + this.a31 * other.a23, this.a11 * other.a31 + this.a21 * other.a32 + this.a31 * other.a33, this.a12 * other.a11 + this.a22 * other.a12 + this.a32 * other.a13, this.a12 * other.a21 + this.a22 * other.a22 + this.a32 * other.a23, this.a12 * other.a31 + this.a22 * other.a32 + this.a32 * other.a33, this.a13 * other.a11 + this.a23 * other.a12 + this.a33 * other.a13, this.a13 * other.a21 + this.a23 * other.a22 + this.a33 * other.a23, this.a13 * other.a31 + this.a23 * other.a32 + this.a33 * other.a33);
	}

}

PerspectiveTransform.quadrilateralToQuadrilateral = function (x0, y0, x1, y1, x2, y2, x3, y3, x0p, y0p, x1p, y1p, x2p, y2p, x3p, y3p) {
	var qToS = this.quadrilateralToSquare(x0, y0, x1, y1, x2, y2, x3, y3);
	var sToQ = this.squareToQuadrilateral(x0p, y0p, x1p, y1p, x2p, y2p, x3p, y3p);
	return sToQ.times(qToS);
}

PerspectiveTransform.squareToQuadrilateral = function (x0, y0, x1, y1, x2, y2, x3, y3) {
	var dy2 = y3 - y2;
	var dy3 = y0 - y1 + y2 - y3;
	if (dy2 == 0.0 && dy3 == 0.0) {
		return new PerspectiveTransform(x1 - x0, x2 - x1, x0, y1 - y0, y2 - y1, y0, 0.0, 0.0, 1.0);
	} else {
		var dx1 = x1 - x2;
		var dx2 = x3 - x2;
		var dx3 = x0 - x1 + x2 - x3;
		var dy1 = y1 - y2;
		var denominator = dx1 * dy2 - dx2 * dy1;
		var a13 = (dx3 * dy2 - dx2 * dy3) / denominator;
		var a23 = (dx1 * dy3 - dx3 * dy1) / denominator;
		return new PerspectiveTransform(x1 - x0 + a13 * x1, x3 - x0 + a23 * x3, x0, y1 - y0 + a13 * y1, y3 - y0 + a23 * y3, y0, a13, a23, 1.0);
	}
}

PerspectiveTransform.quadrilateralToSquare = function (x0, y0, x1, y1, x2, y2, x3, y3) {
	// Here, the adjoint serves as the inverse:
	return this.squareToQuadrilateral(x0, y0, x1, y1, x2, y2, x3, y3).buildAdjoint();
}

function DetectorResult(bits, points) {
	this.bits = bits;
	this.points = points;
}

function Detector(image) {
	this.image = image;
	this.resultPointCallback = null;

	this.sizeOfBlackWhiteBlackRun = function (fromX, fromY, toX, toY) {
		var image = this.image
		// Mild variant of Bresenham's algorithm;
		// see http://en.wikipedia.org/wiki/Bresenham's_line_algorithm
		var steep = Math.abs(toY - fromY) > Math.abs(toX - fromX);
		if (steep) {
			var temp = fromX;
			fromX = fromY;
			fromY = temp;
			temp = toX;
			toX = toY;
			toY = temp;
		}

		var dx = Math.abs(toX - fromX);
		var dy = Math.abs(toY - fromY);
		var error =  - dx >> 1;
		var ystep = fromY < toY ? 1 :  - 1;
		var xstep = fromX < toX ? 1 :  - 1;
		var state = 0; // In black pixels, looking for white, first or second time
		for (var x = fromX, y = fromY; x != toX; x += xstep) {

			var realX = steep ? y : x;
			var realY = steep ? x : y;
			if (state == 1) {
				// In white pixels, looking for black
				if (image.data[realX + realY * image.width]) {
					state++;
				}
			} else {
				if (!image.data[realX + realY * image.width]) {
					state++;
				}
			}

			if (state == 3) {
				// Found black, white, black, and stumbled back onto white; done
				var diffX = x - fromX;
				var diffY = y - fromY;
				return Math.sqrt((diffX * diffX + diffY * diffY));
			}
			error += dy;
			if (error > 0) {
				if (y == toY) {
					break;
				}
				y += ystep;
				error -= dx;
			}
		}
		var diffX2 = toX - fromX;
		var diffY2 = toY - fromY;
		return Math.sqrt((diffX2 * diffX2 + diffY2 * diffY2));
	}

	this.sizeOfBlackWhiteBlackRunBothWays = function (fromX, fromY, toX, toY) {
		var image = this.image

		var result = this.sizeOfBlackWhiteBlackRun(fromX, fromY, toX, toY);

		// Now count other way -- don't run off image though of course
		var scale = 1.0;
		var otherToX = fromX - (toX - fromX);
		if (otherToX < 0) {
			scale = fromX / (fromX - otherToX);
			otherToX = 0;
		} else if (otherToX >= image.width) {
			scale = (image.width - 1 - fromX) / (otherToX - fromX);
			otherToX = image.width - 1;
		}
		var otherToY = Math.floor(fromY - (toY - fromY) * scale);

		scale = 1.0;
		if (otherToY < 0) {
			scale = fromY / (fromY - otherToY);
			otherToY = 0;
		} else if (otherToY >= image.height) {
			scale = (image.height - 1 - fromY) / (otherToY - fromY);
			otherToY = image.height - 1;
		}
		otherToX = Math.floor(fromX + (otherToX - fromX) * scale);

		result += this.sizeOfBlackWhiteBlackRun(fromX, fromY, otherToX, otherToY);
		return result - 1.0; // -1 because we counted the middle pixel twice
	}

	this.calculateModuleSizeOneWay = function (pattern, otherPattern) {
		var moduleSizeEst1 = this.sizeOfBlackWhiteBlackRunBothWays(Math.floor(pattern.X), Math.floor(pattern.Y), Math.floor(otherPattern.X), Math.floor(otherPattern.Y));
		var moduleSizeEst2 = this.sizeOfBlackWhiteBlackRunBothWays(Math.floor(otherPattern.X), Math.floor(otherPattern.Y), Math.floor(pattern.X), Math.floor(pattern.Y));
		if (isNaN(moduleSizeEst1)) {
			return moduleSizeEst2 / 7.0;
		}
		if (isNaN(moduleSizeEst2)) {
			return moduleSizeEst1 / 7.0;
		}
		// Average them, and divide by 7 since we've counted the width of 3 black modules,
		// and 1 white and 1 black module on either side. Ergo, divide sum by 14.
		return (moduleSizeEst1 + moduleSizeEst2) / 14.0;
	}

	this.calculateModuleSize = function (topLeft, topRight, bottomLeft) {
		// Take the average
		return (this.calculateModuleSizeOneWay(topLeft, topRight) + this.calculateModuleSizeOneWay(topLeft, bottomLeft)) / 2.0;
	}

	this.distance = function (pattern1, pattern2) {
		var xDiff = pattern1.X - pattern2.X;
		var yDiff = pattern1.Y - pattern2.Y;
		return Math.sqrt((xDiff * xDiff + yDiff * yDiff));
	}
	this.computeDimension = function (topLeft, topRight, bottomLeft, moduleSize) {

		var tltrCentersDimension = Math.round(this.distance(topLeft, topRight) / moduleSize);
		var tlblCentersDimension = Math.round(this.distance(topLeft, bottomLeft) / moduleSize);
		var dimension = ((tltrCentersDimension + tlblCentersDimension) >> 1) + 7;
		switch (dimension & 0x03) {

			// mod 4
		case 0:
			dimension++;
			break;
			// 1? do nothing

		case 2:
			dimension--;
			break;

		case 3:
			throw "Error";
		}
		return dimension;
	}

	this.findAlignmentInRegion = function (overallEstModuleSize, estAlignmentX, estAlignmentY, allowanceFactor) {
		var image = this.image
		// Look for an alignment pattern (3 modules in size) around where it
		// should be
		var allowance = Math.floor(allowanceFactor * overallEstModuleSize);
		var alignmentAreaLeftX = Math.max(0, estAlignmentX - allowance);
		var alignmentAreaRightX = Math.min(image.width - 1, estAlignmentX + allowance);
		if (alignmentAreaRightX - alignmentAreaLeftX < overallEstModuleSize * 3) {
			throw "Error";
		}

		var alignmentAreaTopY = Math.max(0, estAlignmentY - allowance);
		var alignmentAreaBottomY = Math.min(image.height - 1, estAlignmentY + allowance);

		const AlignmentPatternFinder = require('./AlignmentPatternFinder')
		var alignmentFinder = new AlignmentPatternFinder(this.image, alignmentAreaLeftX, alignmentAreaTopY, alignmentAreaRightX - alignmentAreaLeftX, alignmentAreaBottomY - alignmentAreaTopY, overallEstModuleSize, this.resultPointCallback);
		return alignmentFinder.find();
	}

	this.createTransform = function (topLeft, topRight, bottomLeft, alignmentPattern, dimension) {
		var dimMinusThree = dimension - 3.5;
		var bottomRightX;
		var bottomRightY;
		var sourceBottomRightX;
		var sourceBottomRightY;
		if (alignmentPattern != null) {
			bottomRightX = alignmentPattern.X;
			bottomRightY = alignmentPattern.Y;
			sourceBottomRightX = sourceBottomRightY = dimMinusThree - 3.0;
		} else {
			// Don't have an alignment pattern, just make up the bottom-right point
			bottomRightX = (topRight.X - topLeft.X) + bottomLeft.X;
			bottomRightY = (topRight.Y - topLeft.Y) + bottomLeft.Y;
			sourceBottomRightX = sourceBottomRightY = dimMinusThree;
		}

		var transform = PerspectiveTransform.quadrilateralToQuadrilateral(3.5, 3.5, dimMinusThree, 3.5, sourceBottomRightX, sourceBottomRightY, 3.5, dimMinusThree, topLeft.X, topLeft.Y, topRight.X, topRight.Y, bottomRightX, bottomRightY, bottomLeft.X, bottomLeft.Y);

		return transform;
	}

	this.sampleGrid = function (image, transform, dimension) {
		return require('./GridSampler').sampleGrid3(image, dimension, transform);
	}

	this.processFinderPatternInfo = function (info) {

		var topLeft = info.TopLeft;
		var topRight = info.TopRight;
		var bottomLeft = info.BottomLeft;

		var moduleSize = this.calculateModuleSize(topLeft, topRight, bottomLeft);
		if (moduleSize < 1.0) {
			throw "Error";
		}
		var dimension = this.computeDimension(topLeft, topRight, bottomLeft, moduleSize);
		var provisionalVersion = require('./Version').getProvisionalVersionForDimension(dimension);
		var modulesBetweenFPCenters = provisionalVersion.DimensionForVersion - 7;

		var alignmentPattern = null;
		// Anything above version 1 has an alignment pattern
		if (provisionalVersion.AlignmentPatternCenters.length > 0) {

			// Guess where a "bottom right" finder pattern would have been
			var bottomRightX = topRight.X - topLeft.X + bottomLeft.X;
			var bottomRightY = topRight.Y - topLeft.Y + bottomLeft.Y;

			// Estimate that alignment pattern is closer by 3 modules
			// from "bottom right" to known top left location
			var correctionToTopLeft = 1.0 - 3.0 / modulesBetweenFPCenters;
			var estAlignmentX = Math.floor(topLeft.X + correctionToTopLeft * (bottomRightX - topLeft.X));
			var estAlignmentY = Math.floor(topLeft.Y + correctionToTopLeft * (bottomRightY - topLeft.Y));

			// Kind of arbitrary -- expand search radius before giving up
			for (var i = 4; i <= 16; i <<= 1) {
				//try
				//{
				alignmentPattern = this.findAlignmentInRegion(moduleSize, estAlignmentX, estAlignmentY, i);
				break;
				//}
				//catch (re)
				//{
				// try next round
				//}
			}
			// If we didn't find alignment pattern... well try anyway without it
		}

		var transform = this.createTransform(topLeft, topRight, bottomLeft, alignmentPattern, dimension);

		var bits = this.sampleGrid(this.image, transform, dimension);

		var points;
		if (alignmentPattern == null) {
			points = new Array(bottomLeft, topLeft, topRight);
		} else {
			points = new Array(bottomLeft, topLeft, topRight, alignmentPattern);
		}
		return new DetectorResult(bits, points);
	}

	this.detect = function () {
		const FinderPatternFinder = require('./FinderPatternFinder')
		var info = new FinderPatternFinder().findFinderPattern(image);
		return this.processFinderPatternInfo(info);
	}
}

module.exports = Detector
